Technical Field
This disclosure relates to cardiopulmonary instruments and more particularly to methods and devices for automatic cardiopulmonary resuscitation (CPR), which include compact features for efficient and ease of usage.
Description of the Related Art
Mechanical cardiopulmonary resuscitation (CPR) compression devices provide many clinical and practical advantages over manual CPR. Per 2010 guidelines from the American Heart Association (AHA), the CPR compression rate should be at least 100 compressions per minute with a minimum depth of 5 centimeters (for adults). Studies have found that manual CPR is frequently performed too slowly and without adequate depth to ensure good perfusion. In addition, even if manual compressions are performed to AHA guidelines, caregivers tire quickly. Mechanical CPR devices provide compressions consistent with AHA guidelines over long periods of time.
A variety of technologies have been applied to develop mechanical CPR devices, each with significant disadvantages in terms of weight, size, portability, and run times. Most current generation CPR devices have switched to electro-mechanically powered compression mechanisms. These devices use battery-powered motors and provide precise control and adjustability of compression rate and depth. However, these first generation electro-mechanical CPR devices are heavy, large, and difficult to set up on the patient.
Electromechanical CPR devices typically weigh about 15 pounds or more. Due to this weight, if the device sits directly on the patient's chest, it will provide a pre-load that will interfere with the efficacy of the CPR compressions. High quality chest compressions include two phases: compression and release. During the compression cycle, compression of the chest in the area of the sternum squeezes the heart chambers so that oxygenated blood flows to vital organs. During the release cycle, the chest expands and the heart chambers refill with blood. If a heavy compression unit sits on the patient's chest, the chest expansion is limited, and therefore the quality of CPR is reduced, i.e., perfusion is reduced because the amount of blood returning to the heart chambers is reduced. Many conventional electromechanical devices have high centers of gravity, which can adversely affect their stability during operation and transport. This can contribute to rocking of the compression device, potentially adversely affecting therapy and/or make it more difficult for the caregivers to operate.
In addition, the size and weight of any portable medical device, especially those used in a pre-hospital and emergency medical services (EMS) environment, can significantly affect the acceptability of the device to the caregiver. Devices such as a portable defibrillator, monitor or an automated CPR device must fit inside the limited storage space of an ambulance or fire truck. In some locations, EMS caregivers must carry these devices, in addition to many other items, up many flights of stairs to reach their patient. Added weight and size slows down caregivers, which in turn may have a negative effect upon the patient's health. Every second counts when the patient has suffered sudden cardiac arrest.